In basic solid fuel, pressurized fluidized bed (PFB) combustion systems for gas turbine engines of on the order of 50 megawatts and higher, vitiated air is produced by fluidizing or combusting coal in a pressure vessel outside the engine in 100% of the discharge of the compressor of the engine diverted outside of the case thereof to the PFB. The turbine inlet temperature of such PFB produced vitiated air is unacceptably low because the fluidized bed reaction temperature must be below the slagging temperature of coal, about 1600 degrees F. To increase the turbine inlet temperature of PFB produced vitiated air, systems have been proposed in which the vitiated air is further heated in a topping combustor outside the engine. In such systems, topping combustor fuel may be supplied separately or generated in a carbonizer in which coal is partially combusted in a portion of compressor discharge to produce combustible fuel gas. Char, the residue of the carbonizer, is suitable for further combustion in a PFB to produce the low temperature vitiated air which, in turn, is heated in the topping combustor to an acceptably high turbine inlet temperature. Such PFB systems, however, divert 100% of compressor discharge outside of the engine and are, therefore, burdened by high costs for fabricating and maintaining structure to contain and transfer large quantities of compressed air and high temperature vitiated air. In addition, major structural modifications are required in the engine to accommodate 100% diversion of compressor discharge. A solid fuel, PFB combustion system according to this invention minimizes costs by diverting less than 100% of compressor discharge outside the engine and by minimizing structural modifications in the engine.